1. Technical Field
The present disclosure relates to a safety system for a vehicle to detect and warn of a potential collision with an object in the path of travel of the vehicle as part of a driver assistance system.
2. Background Information
Driver assistance systems (DAS) typically include lane departure warning (LDW), Automatic High-beam Control (AHC), pedestrian recognition, forward collision warning (FCW) and pedestrian detection. Vehicle detection, pedestrian detection and traffic sign recognition algorithms may share a common general structure: an initial candidate detection followed by more computationally intensive classification of the initial candidate. Obstacle detection may also be performed using various structure-from-motion algorithms.
Lane departure warning (LDW) systems are designed to give a warning in the case of unintentional lane departure. The warning is given when the vehicle crosses or is about to cross the lane marker. Driver intention is determined based on use of turn signals, change in steering wheel angle, vehicle speed and brake activation.
Traffic sign recognition (TSR) modules are designed typically to detect speed limit signs and end-of-speed limit signs on highways, country roads and urban settings. Partially occluded, slightly twisted and rotated traffic signs are preferably detected. Systems implementing traffic sign recognition (TSR) may or should ignore the following signs: signs on truck/buses, exit road numbers, minimum speed signs, and embedded signs. A traffic sign recognition (TSR) module which focuses on speed limit signs may not have a specific detection range requirement because speed limit signs only need to be detected before they leave the image.
The core technology behind forward collision warning (FCW) systems and headway distance monitoring is vehicle detection. A key component of a typical forward collision warning (FCW) algorithm is the estimation of distance from a single camera and the estimation of scale change from the time-to-contact/collision (TTC) as disclosed for example in U.S. Pat. No. 7,113,867.
Structure-from-Motion (SfM) refers to methods for recovering three-dimensional information of a scene that has been projected onto the back focal plane of a camera. The structural information derived from a SfM algorithm may take the form of a set of projection matrices, one projection matrix per image frame, representing the relationship between a specific two-dimensional point in the image plane and its corresponding three-dimensional point. SfM algorithms rely on tracking specific image features from image frame to image frame to determine structural information concerning the scene.